President Rajaonarimampianina labels attack on national day, in which 84 people were wounded, an "act of terrorism".

Two teenagers were killed and more than 80 wounded in a grenade attack in Madagascar's capital during the country's national day celebrations, in what the president called "an act of terrorism".

The blast on Sunday struck the Mahamasina municipal stadium in Antananarivo at around 16:00GMT, just as a free concert was taking place to mark the nation's 56th anniversary of independence from France.

President Hery Rajaonarimampianina, who visited the wounded victims in hospital, blamed the attack on tensions with political opponents in the Indian Ocean island nation.

"There may be differences of opinion between us, but these acts of destabilisation are unacceptable," he said in a statement broadcast on national television, describing the attack as "not just a destabilising act but an act of terrorism".

Pleading for calm, he added: "We will not respond to violence with violence".

According to the gendarmerie, the attack killed two teenagers aged 16 and 18, while 84 people were wounded.

A military parade was held at the stadium earlier in the day.

"The explosion was caused by a grenade," said general Anthony Rakotoarison, head of security and intelligence with the national gendarmerie. "We consider this a terrorist act," he added.

2014 attack

The last attack to hit Madagascar was in January 2014 when a grenade blast killed a toddler and wounded several other people outside the same stadium that was targeted on Sunday.

No arrests were ever made in connection with that attack and there was no claim of responsibility.

Madagascar, one of the world's poorest countries, is slowly getting back on its feet after a lengthy period of political instability triggered by the 2009 removal of president Marc Ravalomanana by Antananarivo's then-mayor Andry Rajoelina.

Rajoelina led a transitional government until late 2013, when a new election that was designed to resolve complex struggles brought Rajaonarimampianina to power

International donors, on which the country relies heavily, only recently returned to Madagascar after withdrawing over the 2009 turmoil, and the economy is starting to show the first signs of recovery.